Installed today - so far, so good. Definitely faster than 7, and some interesting features too.
Will let you know if bugs start coming out of the walls...
One thing to note - it renders pages a lot like Firefox. For example, I just realized that on the Six news stuff, FF doesn't see the bullet points in front of the paragraphs. Neither does IE8. Also, the font size on the link titles on the right have grown smaller.
(IE8 has a compatibility view tab which switches back to rendering in IE7, a nice feature to test things out)